Conventional sacrificial anodes are available in the form of discrete galvanic zinc anodes which are embeddable within steel-reinforced concrete. These anodes are typically formed as solid cast blocks of zinc with limited surface area compared to their weight, or are made from one or more pieces of expanded zinc mesh gathered together. Both types of zinc anodes are embedded within a casing of conductive mortar which facilitates the corrosion of the anode material and enables a protective galvanic current to flow when the anodes are connected to steel reinforcement within a concrete covering. Examples are shown in U.S. Pat. Nos. 6,193,857 and 6,022,469.
Conventional discrete embeddable anodes typically do not have any mechanism for spacing them apart from the steel reinforcing rods or “rebars” they are fitted to, apart from the thickness of the covering mortar and/or an integral plastic barrier. Close proximity to the steel reinforcing member or rebar increases galvanic activity (and hence protection) in the immediate vicinity of the sacrificial anode at the expense of activity and protection applied to more distant parts of the steel reinforcement.
One product currently on the market achieves greater anode surface area by using pieces of expanded zinc mesh soldered to one or more ductile iron wires that carry the protective current to the steel reinforcement. Another product currently on the market makes use of an integral plastic barrier to inhibit the passage of protective current in areas in the immediate vicinity of the steel anode interface, forcing the current further away from the point of contact. While these conventional anodes function adequately, it would be desirable to improve the useful life and function of such anodes while facilitating their proper installation and spacing from a steel structure, such as a steel reinforcing bar embedded in concrete.